Crashing Beneath the Rear or Side of a Truck or Trailer
When a passenger car penetrates beneath... or "underrides"...the tall rear or side of a large truck or trailer, it often causes severe to fatal head trauma, or even decapitation. Typical defective guards are too high above the ground, too narrow across the rear, and too weak. And there are no side guards at all.
Typically of many rear underride accidents, such as shown below, is when the driver tries at the last second to steer around the left side or right side of the slowly-moving or stopped trailer ahead. The passenger vehicle impacts the outboard portion of the rear guard, which bends or breaks, acting much like a swinging gate... and the underride tragedy occurs.
Compliance with the minimum requirements Federal Motor Vehicle Safety Standard 223-224 does not ensure a reasonably safe rear guard. FMVSS 223-224 requires only a "slow push" test at centrally-located portions of the guard, at only 22,400 pounds. There are no dynamic test requirements to accurately reflect the strength needed for offset rear impacts, such as shown in the photo below. I have long urged that the test requirement be at least 60,000 lbs. resistive load at any location across the rear guard. Car-into-trailer crash tests done by the Insurance Institute for Highway Safety (IIHS) in 2010 through 2013 have also shown how weak and ineffective most rear guards are on contemporary trailers.